AMYLOID SUBSTANCE. 69 



7. To a solution of alloxan add some baryta water and 

 solution of baryum nitrate, and observe the formation of 

 a pink-red solution. This, before the spectroscope, 

 shows a specific absorption band covering orange, 

 yellow, green, and blue, and allowing red and a part of 

 blue with violet to pass. 



8. Drop into a concentrated solution of lead acetate 

 heated to boiling a solution of alloxan, and observe the 

 formation of a white precipitate of mesoxalate of lead, 

 and the liberation of acetic acid. From the nitrate 

 urea can be obtained by removal of the lead and evapo- 

 ration of the acetic acid. 



Amyloid substance. 1. Search the brain, spinal 

 marrow, ependyma ventriculorum, ganglion Gasseri, or 

 optic nerve in disease, particularly so called chronic 

 atrophy or locomotor ataxia, by hardening the sub- 

 stance to be examined in strong alcohol, then making 

 the thinnest possible sections with a razor and placing 

 them under the microscope. 



2. Apply tincture of iodine dissolved in iodide of 

 potassium, and observe that no blue starch granules 

 appear. 



3. Wash away the iodine solution by water and apply 

 dilute sulphuric acid, let stand for some time and apply 

 some iodine solution. The amyloid, if present, will 

 now appear in the form of minute blue granules closely 

 resembling the iodised starch corpuscles of wheat. 



4. Compare the reaction of amyloid matter with that 

 of vegetable lignine. 



Animal quinoidine. 1, Treat the part to be exa- 



